View
20
Download
0
Category
Tags:
Preview:
DESCRIPTION
Search for TeV-scale bosons in the +- decay channel in CMS. I. Golutvin, P. Moissenz, V. Palichik, M. Savina, and S. Shmatov Joint Institute for Nuclear Research, Dubna. Motivation Extensions of the Standard Model and Beyond the SM Extended Gauge Models (Z ) - PowerPoint PPT Presentation
Citation preview
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, and S. Shmatov
Joint Institute for Nuclear Research, Dubna
MotivationMotivation Extensions of the Standard Model and Beyond the Extensions of the Standard Model and Beyond the SMSM
Extended Gauge Models (ZExtended Gauge Models (Z) ) RS1-scenario (KK-graviton resonance)RS1-scenario (KK-graviton resonance)
Cross-sections and expected ratesCross-sections and expected rates Background (DY)Background (DY) Forward-backward asymmetryForward-backward asymmetry Angular distributionsAngular distributions ConclusionsConclusions
Search for TeV-scale bosons in the Search for TeV-scale bosons in the ++- decay channel in CMS- decay channel in CMS
General MotivationsGeneral MotivationsGeneral MotivationsGeneral Motivations
the current measurements (D0, CDF) of the the current measurements (D0, CDF) of the Drell-YanDrell-Yan cross-cross-
section at high dilepton invariant mass (up to 0.6 TeV) section at high dilepton invariant mass (up to 0.6 TeV) are are
in good agreement with the Standard Model predictions in good agreement with the Standard Model predictions (NLO) (NLO)
study of high mass dileptons at LHC allows one to test study of high mass dileptons at LHC allows one to test the the SMSM
at a new energy scale (at a new energy scale (Drell-Yan Drell-Yan production up to production up to 1 1 4 4 TeV TeV
invariant mass region) invariant mass region)
dilepton continuum is very sensitive to any modifications dilepton continuum is very sensitive to any modifications of of
SM Lagrangian induced by new physics beyond the SMSM Lagrangian induced by new physics beyond the SM Extended gauge models (Extended gauge models (Sequential Standard Model, Sequential Standard Model,
Left-Right Model, E6-, S0(10)- based modelsLeft-Right Model, E6-, S0(10)- based models)) new gauge bosons, Wnew gauge bosons, W and Z and Z horizontal bosons, Rhorizontal bosons, R new Higgs bosons, H++, H--new Higgs bosons, H++, H--
Large extra dimension scenarios Large extra dimension scenarios ((ADD, RS, NLED’sADD, RS, NLED’s)) Compositeness modelsCompositeness models
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
Motivations for dimuon studyMotivations for dimuon studyMotivations for dimuon studyMotivations for dimuon study
many models beyond the SM predicted new heavy (m ~ many models beyond the SM predicted new heavy (m ~ a few a few
TeV) boson statesTeV) boson states Extended gauge models (Extended gauge models (ZZ, spin1-state, from SSM, LRM, , spin1-state, from SSM, LRM,
E6E6) ) C.-E. Wulz, CMS-NOTE 1993/107C.-E. Wulz, CMS-NOTE 1993/107
Large extra dimension scenarios, Randall-Sundrum RS1 Large extra dimension scenarios, Randall-Sundrum RS1 ((GGKKKK-graviton, spin-2 state-graviton, spin-2 state))
P.Traczyk and G.Wrochna, CMS-NOTE 2002/003,P.Traczyk and G.Wrochna, CMS-NOTE 2002/003, M.-C.Lemaire and J.-P.Pansart, CMS-NOTE 2002/020M.-C.Lemaire and J.-P.Pansart, CMS-NOTE 2002/020
di-muon channel is a clear and simple signature of di-muon channel is a clear and simple signature of resonancesresonances
concentrate within certain mass intervalconcentrate within certain mass interval good isolationgood isolation both muons come from the same vertexboth muons come from the same vertex good effective mass and angular resolution for good effective mass and angular resolution for high-phigh-pTT muons muons low backgroundlow background
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
Signal (Z´) and background (DY) simulation
Pythia 6.217, Pythia 6.217, qqbar Z´ (´ (no jet veto, other production mechanisms qg qZ´ ´
will be added in the future) , ,
CTEQ5L, K(Z´)= 1, KCTEQ5L, K(Z´)= 1, KDY DY = 1.38= 1.38
Initial- and final-state radiation are switched onInitial- and final-state radiation are switched on
SSM: Br(Br(++-) = 0.032-) = 0.032 LRM: assume the same couplings for both left- and right-handed sectors:
gL / gR= 1 (value as in the SM) Br(Br(++-) = 0.023-) = 0.023
-, -, and -models: couplings from J.Rosner, Phys. Rev. D35, 2244 (1987)
GGKKKK simulation simulation
Pythia 6.217, Pythia 6.217, qqbar GKK, gg, gg GKK, qqbar gGKK, qg qGKK, gg gGKK
Detector Response and ReconstructionDetector Response and Reconstruction Fast non-GEANT simulationFast non-GEANT simulation: : CMSJET 4.7CMSJET 4.7 (detector response are taken (detector response are taken into into
account by smearing of energy/momentum according to some resolution) account by smearing of energy/momentum according to some resolution)
Simulation Tools Simulation Tools
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
SM BackgroundSM Background main SM background comes from DY process with large invariant
dilepton (+-) masses an irreducible SM background goes down rapidly when M+- grows at present, no exact NLO and NNLO matrix elements have been used,
we have used K = 1.38 (from Tevatron data) for M > 1 TeV (M+- > 1 TeV) = 9.07 fb (Pythia 6.217)
Di-bosons: ZZ, WWDi-bosons: ZZ, WW, , ZW (is not taken into account)ZW (is not taken into account)
(M+- > 1 TeV) = 0.4 fb, less then 4.5 % of Drell-Yan, K=1.4-1.9
ttbar-quark (is not taken into account)(is not taken into account)
(M+- > 1 TeV) = 0.3 fb, ~ 3 % of Drell-Yan, K=1.6
BackgroundBackground
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
Z-bosonsZ-bosons
Expected ZExpected Z ++-- Rate RateExpected ZExpected Z ++-- Rate Rate
we assume no exotic fermions (nG=0) for SSM, -, -, -models (Br = 0.032)
number of extra fermion generations is nG=3 (right-handed fermions) for LRM (Br = 0.023)
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
d/
dM
, fb
/40
GeV
M, GeV
DY + Z
Drell-Yan
,/M ~ 3 %
no detector response
no kinematics cuts
1000 2000 3000 40000,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
< 2.4, pT > 20 GeV
3rec
mass interval
< 2.4
Eff
icie
nc
y
Z' Mass, GeV
Pythia6.217 + CMSJET 4.7
Discovery Limit for ZDiscovery Limit for Z
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
d/
dM
, fb
/GeV
Pythia 6.217 + CMSJET 4.7Generated
M, GeVBackground, DY
0 1000 2000 3000 4000 5000
10-2
10-1
100
101
102
103
ZSSM
and Z, Pythia6.217
Z and Z, Pythia6.217
5 CMS limit for 1000 fb-1
5 CMS limit for 100 fb-1
5 CMS limit for 10 fb-1
tot
Br
, fb
Z' mass, GeV
Nmin = max (5NB, 10)
NB is the number of Drell-Yan background inside 3rec mass
window after cuts
Response
|| 2.4, pT 20 GeV
10 fb-1 100 fb-1 1000 fb-1
SSM, -model 3.01 3.96 5.0
- and -models 2.54 3.46 4.48
LR-model 2.96 4.08 5.35The search reach for CMS
(in TeV)
ZZ Forward-Backward Asymmetry Forward-Backward AsymmetryZZ Forward-Backward Asymmetry Forward-Backward Asymmetry
-3 -2 -1 0 1 2 3-0,6
-0,4
-0,2
0,0
0,2
0,4
0,6
-modelAFB
Rapidity
-3 -2 -1 0 1 2 3-0,6
-0,4
-0,2
0,0
0,2
0,4
0,6
-modelAFB
Rapidity
MZ’ = 2.0 TeV
rapidity-dependence of forward-backward asymmetry in Z+- decays for
various models has a very distinctive behaviour
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
)()()()(
)(yByFyByF
yAFB
F(y) is number of with cos(*) > 0,B(y) is number of with cos(*) < 0,* is the angle in the di-muon C.M. (Z rest frame) between the - and one (fixed) of the proton beams,y is Z rapidity
100 fb-1
qqbar Z +-
P. Langacker,R.W. Robinett,J.L.Rosner, PR, D30, 1470
Z rapidity
Z rapidity
Z rapidity
-3 -2 -1 0 1 2 3-0,6
-0,4
-0,2
0,0
0,2
0,4
0,6
LR-modelAFB
RapidityZ rapidity
GKK-resonanceGKK-resonance
GGKKKK graviton production (RS1) graviton production (RS1)GGKKKK graviton production (RS1) graviton production (RS1)
virtual production
the SM exchange by or Z boson interferes with the exchange by graviton (qq GKK +-)
+ /Z0 l-
l+
q
q
GKKq
q
l-
l+
there is also gluon-gluon initiated graviton exchange process which has no the SM analogue (gg GKK +-)
GKKg
g
l-
l+
+
real graviton production, i.e. graviton emission (qq gGKK ,
qg qGKK, gg gGKK with +- + jet in the final state)
GKKg
g g
GKK
g
g g
GKKq
q g
GKK
q
q g
~ 3 % of total graviton
cross-section
~ 10 – 11 %
~ 70 % ~ 7 %
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
1 2 3 4 5
10-1
100
101
102
103
104
105
106(b)
Rat
e (
+- )
(per
yea
r)
Mass, GeV
Expected GExpected GKKKK ++-- Rates RatesExpected GExpected GKKKK ++-- Rates Rates
K=1
5 diagrams were computed (virtual and real graviton production)
Br (GKK +-) = 0.0205
GKK +- rates were computed for the different coupling constantsc = k/MPl = 0.01, 0.02, 0.05, 0.07, 0.1
k is the AdS5 curvature
100 fb-1
Mass, TeV
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
to
t
Br
Lin
t
0.01
0.02
0.050.07
0.1
Discovery Limit for GDiscovery Limit for GKKKKDiscovery Limit for GDiscovery Limit for GKKKK
500 1000 1500 2000 2500 3000 3500
10-2
10-1
100
101
102
103 Pythia6.217, c = 0.01
5 CMS limit for 10 fb-1
5 CMS limit for 100 fb-1
5 CMS limit for 1000 fb-1
B
r
, fb
Graviton mass, GeV
1000 2000 3000 4000 5000 6000
10-2
10-1
100
101
102
103
104
105 Pythia6.217, c = 0.1
5 CMS limit for 10 fb-1
5 CMS limit for 100 fb-1
5 CMS limit for 1000 fb-1
B
r
, fb
Graviton mass, GeV
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
CMS is able to test RS1 scenario up to 1.95 TeV and 3.74 TeV mass limit for c = 0.01 and c = 0.1, respectively, even at 10 fb-1
10 fb-1 100 fb-1 1000 fb-1
c = 0.01 1.95 2.58 3.22
c = 0.1 3.74 4.84 6.25
The search reach for CMS(in TeV)
Angular DistributionsAngular Distributions
Processes angular distributions
qq Z qq gKK
gg gKK
1 + cos2* 1- 3cos2* + 4cos4*
1- cos4*
qq Z (K=1), 100 fb-1
qq, gg GKK (K=1, c=0.1), 10 fb-1
* is the angle of ’s in the Z (GKK) rest frame
cos*
Even
ts
6000 events
m = 1.5 TeV
Z
GKK
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
Theoretical expectations: || 2.4, pT 20 GeV, 3rec
ConclusionsConclusionsConclusionsConclusions
CMS detector performance allows to perform precise measurements of di-muon pairs up to invariant masses of about 4 TeV or even higher
study of a Drell-Yan muon pair production enables to check-up the SM within this mass region
Any deviations from SM predictions (excess or deficit) will indicate the new phenomena beyond SM
extra gauge boson Z can be observed in the dimuon channel with S/B 5 for masses up to 2.5 3.0 for 10 fb-1 TeV 3.5 4.1 TeV for 100 fb-1
integrated luminosity
on the assumption c=0.01 gKK can be observed in the dimuon channel with S/B 5 for masses up to 1.9 for 10 fb-1 and 2.6 TeV for 100 fb-1
forward-backward asymmetry of muons (from Z) can be used for more detailed study of the Z origin model
spin-2 states (graviton) can be distinguished from spin-1 states (Z) by analyzing angular distribution of muons
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
SupplementSupplement
Z-bosonsZ-bosons
Expected ZExpected Z ++-- Rate RateExpected ZExpected Z ++-- Rate Rate
Mass, GeV Number of muon pairs at 100 fb-1
Z’SSM Z’LR Z’ Z’ Z’
500 5.9105 4.2105 5.3105 1.88105
1000 4104 3.1104 3.6104 1.26104
1200 1.8104 1.4104 1.6104 5700
1500 6800 4970 6000 2100
2000 1730 1200 1522 535
2500 670 360 470 166
3000 190 124 170 60
4000 30 20 26 9
5000 8 4 5
we assume no exotic fermions (nG=0) for SSM, -, -, -models (Br = 0.032)
number of extra fermion generations is nG=3 (right-handed fermions) for LRM (Br = 0.023)
no kinematics cuts
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
Signal/Background Events for ZSignal/Background Events for Z
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
d/
dM
, fb
/GeV
d/
dM
, fb
/GeV
M, GeV
Pythia 6.217 + CMSJET 4.7, || 2.4, pT 20 GeV
Generated
ResponseM, GeV
Background, DY
0 1 2 3-1,0-0,9-0,8-0,7-0,6-0,5-0,4-0,3-0,2-0,10,0
-model
AFB
Rapidity
0 1 2 3-0,6
-0,4
-0,2
0,0
0,2
0,4
0,6
0,8
1,0
-model
AFB
Rapidity
0 1 2 3-0,6
-0,4
-0,2
0,0
0,2
0,4
0,6
0,8
1,0
LR-model
AFB
Rapidity
ZZ Forward-Backward Asymmetry Forward-Backward AsymmetryZZ Forward-Backward Asymmetry Forward-Backward Asymmetry
MZ’ = 2.0 TeV
rapidity-dependence of forward-backward asymmetry in Z+- decays for
various models has a very distinctive behaviour
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
)()()()(
)(yByFyByF
yAFB
F(y) is number of with cos(*) > 0,B(y) is number of with cos(*) < 0,* is the angle in the di-muon C.M. (Z rest frame) between the - and one (fixed) of the proton beams,y is Z rapidity
100 fb-1
pp Z +-
P. Langacker,R.W. Robinett,J.L.Rosner, PR, D30, 1470
Z rapidity
Z rapidity
Z rapidity
Z rapidity
ZZ Forward-Backward Asymmetry Forward-Backward AsymmetryZZ Forward-Backward Asymmetry Forward-Backward Asymmetry
-model 0.5 TeV 1.0 TeV 1.5 TeV 3.0 TeV
|y| < 2.8 (-3.4 0.8) 10-4
(-6.2 0.4) 10-3
(-1.7 0.2) 10-2
(-5.9 5.9) 10-2
0.5 < y <1.5 -0.185 0.004
-0.269 0.004
-0.332 0.014
-0.538 0.143
-1.5 < y < -0.5 0.197 0.004
0.269 0.004
0.317 0.004
0.415 0.101
1.5 < y < 2.8 -0.368 0.006
- 0.389 0.012
-0.397 0.053
-1.0 1.0
-2.8 < y < -1.5 0.355 0.006
0.413 0.012
0.457 0.051
1.0 0.7
strong mass-dependence of forward-backward asymmetry in Z+- !!!
|| 2.4, pT 20 GeV, 5rec
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
GKK-resonanceGKK-resonance
Large Extra Dimensions: RS1Large Extra Dimensions: RS1Large Extra Dimensions: RS1Large Extra Dimensions: RS1
Our world is one of the branes embedded into the 5 dimensional anti-de Sitter space (non-factorizable geometry) with curvature k
ds2 = e-2krc dxdx + r2cd2
Configuration assumes 2 branes on the distance zC each from other: one with the positive tension at z = 0, and the other with the negative tension - what is located at zC
SM matter lives on the 4-brane with induced Minkowski metric and the negative brane tension (RS1 scenario). The 4-al gravity in our World is induced by zero graviton mode
A fundamental scale parameter of the theory (not Planck scale)
Kaluza-Klein excitations of the graviton states (GKK) should be observable at collider energies as spin-2 individual resonances with masses mn = ke-
krc xn , where are xn roots of the Bessel functions J1(xn) = 0. First excitation is
m1 = k x1 e-krc = 3.83(k/MPl) ~ a few TeV , where 0.01 < k/MPl < 1
L.Randall and R. Sundrum, Phys. Rev. Lett. 83,3370 (1999), Phys. Rev. Lett. 83,4690 (1999)
Pl
πkrPlπ M
kxceM c
12 *,Λ
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
GGKKKK graviton production (RS1) graviton production (RS1)GGKKKK graviton production (RS1) graviton production (RS1)
virtual graviton: the SM exchange by or Z boson interferes with the exchange by graviton (qq GKK)
there is also gluon-gluon initiated graviton exchange process which has no the SM analogue (gg GKK)
for real graviton production, i.e. graviton emission (qq gGKK,
qg qGKK, gg gGKK)
M (TeV)
, fb
1 c=0.1 (0.01)
1.5,c=0.1 (0.01)
3.0c=0.1(0.01)
ffbar G* 129(1.34)
23(0.24)
0.633(0.006
)
gg G* 567(5.33)
62(0.53)
0.94(0.004
)
qqbar gG*
345(3.29)
65(0.64)
1.84(0.017
)
qg qG* 599(5.78)
72(0.64)
1.05(0.007
)
gg gG* 3350(31.5)
368(3.32)
4.98(0.028
)
total 4990(47.2)
590(5.38)
9.45(0.062
)
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
GGKK KK selection efficiency GGKK KK selection efficiency
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
0 1000 2000 3000 4000 5000
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
|| < 2.4,
3rec
mass interval
c = 0.01
c = 0.1
Eff
icie
ncy
Graviton Mass, GeV
Pythia 6.217 + CMSJET 4.7, || 2.4, pT 20 GeV, 3rec
G ~ mGc2
Signal/Background Events for GSignal/Background Events for GKKKKSignal/Background Events for GSignal/Background Events for GKKKK
Pythia 6.217 + CMSJET 4.7, || 2.4, pT 20 GeV
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
d/
dM
, fb
/GeV
d/
dM
, fb
/GeV
M, GeV
Generated
Response
M, GeV
Background, DY
c = 0.1
c = 0.1
Detector response for GDetector response for GKKKKDetector response for GDetector response for GKKKK
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
0 1000 2000 3000 4000 5000
0
50
100
150
200
250
300
350 ,
GeV c = 0.1, theory
c = 0.1, CMSJET
c = 0.01, theory
c = 0.1, CMSJET
Graviton mass, GeV
Pythia 6.25 + CMSJET 4.7, || 2.4, pT 20 GeV
Angular DistributionsAngular Distributions
Processes angular distributions
qq Z qq gKK
gg gKK
1 + cos2* 1- 3cos2* + 4cos4*
1- cos4*
qq Z (K=1), 100 fb-1
qq, gg GKK (K=1, c=0.1), 10 fb-1
* is the angle of ’s in the Z (GKK) rest frame
cos*
Even
ts6000 events
m = 1.5 TeV
Z
GKK
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
Theoretical expectations:
F(x) = A0 + A1x + A2x2 +A3x3 + A4x4
State A0 A1 A2 A3 A4
qq Z 412 9 -2.45 22 995 62 2.57 32 -1140 67
qq, gg gKK 710 11
-0.35 22 -318 61 0.36 30 -264 62
|| 2.4, pT 20 GeV, 3rec
Angular DistributionsAngular Distributions* is the angle of ’s in the GKK rest frame
Even
ts
cos*
N 5.8104
pT > 20 isequivalent topT > 100 GeV
qq, gg GKK (K=1, c=0.1)
m = 1.5 TeV
all
|| < 2.4 || < 1.4
100 fb-1
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
Z (500)GKK (3000)
Full ORCA (L3, muon system + tracker) reconstruction
Mass reconstruction in ORCA 6.3.0Mass reconstruction in ORCA 6.3.0
Pythia
ORCA
I. Golutvin, P. Moissenz, V. Palichik, M. Savina, S. Shmatov Prague, July 10, 2003
ORCA reconstruction of high-pT muons still to be tuned !!!
Invariant mass of muon pairs from Pythia
Full ORCA reconstruction of invariant mass
Z (500) Z (500)
Z (1200) Z (1200)
gKK (3000)
Mass reconstruction in ORCA 6.3.0Mass reconstruction in ORCA 6.3.0
Recommended